1. Field of the Invention
The present invention relates generally to the field of agriculture. More particularly, it concerns controlling flowering time in sorghum as well as producing sorghum hybrids with desired flowering times.
2. Description of Related Art
Biomass yield is one of the most important attributes of a biomass or bioenergy crop designed to accumulate ligno-cellulose and fermentable sugars for conversion to biofuels or bioenergy. Growth duration is a determinant of biomass yield, therefore non-flowering plants or plants that flower late in a growing season accumulate the most biomass assuming environmental conditions allow yield potential to be expressed.
Vegetative growth (e.g. leaves and stems) of the plant ceases once sorghum reaches anthesis (flowering). After flowering, products of photosynthesis (hexoses, sugars) and nitrogen assimilation can be stored or used for grain production. If the storage capacity for and utilization of hexoses for grain filling and respiration is less than the plant's capacity to synthesize hexoses through photosynthesis, the rate of biomass accumulation will decrease limiting yield. Moreover, biomass accumulation is reduced once grain filling has been completed (unless ratooning follows grain production). Stalk sugar yield in sweet sorghum generally peaks at grain maturity so flowering helps maximize yield. Therefore, there is a need to produce bioenergy sweet sorghum hybrids with optimal flowering times for each growing environment and to meet the needs of sugar mills and to enable mill operation for a longer duration each year.
A non-flowering or late flowering bioenergy sorghum crop grown for biomass production will continue to accumulate biomass in the form of larger vegetative plants until adverse environmental conditions (e.g., drought, cold) inhibit photosynthesis. It is estimated that late/non-flowering biomass sorghum will generate more than two times the biomass accumulated by photoperiod insensitive early flowering grain sorghum per acre assuming reasonable growth conditions throughout the growing season. Therefore, there is a need for producing late or non-flowering sorghum.